GENERAL GEOLOGY 
39 
granite cliffs at Cape Chibukak, at the west end of the 
island, the granite being like that in Plover Bay. 1 He saw 
this overlain by horizontal brownish or reddish stratified 
materials, probably scoriaceous or agglomeratic. Capt. 
Hooper and Dr. Muir report having seen volcanic cones 
on the island. 2 
If Dr. Muir is right in the opinion that an ice-sheet 
covered the region, the boulders of this shingle may be 
erratics of remote origin; but according to the view of 
Dr. Dawson and Mr. Gilbert that there has been no 
general glaciation, the boulders are of local origin. 
Following is a list of the rocks: 
METAMORPHIC ROCKS 
(a) Dolomitic marble . A white fine-grained statuary marble, 
slightly flamed with grey streaks, effervescing only slightly with strong 
acid. 
(b) Marble . Clear grey fine-grained massive crystalline limestone. 
(c) Black crystalline limestone full of small spots of white crystal¬ 
line limestone, mostly angular, but many seeming to be sections of 
crinoid stems and small Chagtetes-like corals (213). The section 
shows the presence of other, but indeterminate, fossils. 
(d) Malacolite contact rock. Kalk-silikat-hornfels (209). The 
rock seems to be a common limestone banded regularly in white and 
black layers about one-eighth inch thick and slightly pyritous. Under 
the microscope it is seen to be made up of a uniform, rounded-granular 
mass of colorless pyroxene grains (with some biotite scales), which 
are finer in the dark layers (in which there are a few graphite grains) 
and coarser in the white layers and in veins branching from the latter. 
A similar contact rock was found by Mr. Palache on contact of 
tonalite and the Paleozoic limestone in Glacier Bay. It makes fine 
blocks banded in flat black and white layers one-fourth inch thick. 
( e ) Reddish-brown fine-grained micaceous rock like the darker 
layers in d. 
(f) Dark grey cherty slate with white spots that seem like traces 
of fossils (214). 
! Bull. Geol. Soc. Am., vol. v, p. 138, 1894. 
2 Report of the Cruise of the Corwin, 1881, pp. 33, 140, 1884. 
